Monoclonal Gammopathy of Undetermined Significance (MGUS) is one of the plasma cell dyscrasias. An isolated finding of a monoclonal para-protein in serum or urine is the hallmark finding in MGUS. Most often it is found incidentally during an unrelated medical evaluation and/ or investigation to find a cause for neuropathy, anaemia, rashes, vasculitis or elevated Erythrocyte Sedimentation Rate (ESR). This case report illustrates an evaluation of a patient with persistently elevated prothrombin time has eventually lead to a diagnosis of MGUS.